In a photoresist step that is one of semiconductor manufacturing steps, a resist liquid is applied to a surface of a semiconductor wafer (hereinafter referred to as “wafer”) as a process object to form a resist film thereon, and the resist film thus obtained is exposed with a predetermined pattern, and is then developed to form a resist pattern.
Some processing liquid supplying apparatus, which ejects a processing liquid, such as a resist liquid or a developing liquid, to a wafer via a nozzle (ejecting part), is configured to supply the processing liquid from a chemical liquid container (processing liquid source) to the nozzle by using a feed pump. For example, JP2008-305980A (see paragraph [0022] and FIG. 2) describes a chemical liquid supplying system, in which a piston is mounted on one end of a bellows body disposed in a container, and a resist liquid is supplied to a coating nozzle by expanding and contracting the bellows body by the piston. In addition, in a chemical liquid supplying system described in JP2012-151197A (see paragraphs [0035] and [0041] and FIGS. 4 and 5), a resist liquid is supplied to an ejecting nozzle by using a diaphragm pump having a diaphragm that reciprocates in a pump chamber.
In a reciprocation pump of like the aforementioned type, a part of the suctioned processing liquid may remain in a dead space in the pump. If the pump does not discharge therefrom all the processing liquid, particles, such as those originated from chips generated during fabrication of the pump and remaining in the pump immediately after installation thereof, stagnate in the pump together with a processing liquid for a long period of time, which delays starting of the wafer processing and/or invites contamination.
A tube pump is known as a pump in which a processing liquid is less likely to stagnate. The tube pump disadvantageously has a large pulsation, so that it is not suitable, in general, for use as a pump that must supply a predetermined amount of a processing liquid stably to each wafer at a suitable timing. JP2003-118147A (see paragraphs 0025 and 0029 and FIGS. 3 to 5) describes that a squeezing roller presses a resilient tube to discharge an ink from a recording head to a waste ink treatment member. However, this document does not describe a technique for stably supplying a processing liquid to a process object.